The
rule in Hastings-Bass (by which a trustee’s exercise of discretion may be
ineffective for failure to take into account relevant considerations) only
applies if the trustee’s mistake is sufficiently serious to be a breach of
duty.Here trustees had taken
professional advice and could not be said to have acted in breach of duty.But the advice had not addressed
adverse tax consequences and voluntary dispositions undertaken relying on the
advice could be set aside for mistake.Although mere ignorance is insufficient to set aside such a disposition
for mistake, conscious belief or tacit assumption is enough and could be
inferred.